The invention relates to a conversion device and a communications network having the conversion device. Modern motor vehicles have a plurality of regulating and control devices, and a plurality of sensors which, for example, may also include a video camera or several video cameras. Modern motor vehicles may also have devices for the purpose of information transmission or entertainment of vehicle occupants, such as a radio and/or a video playback device. Furthermore, navigation devices are also regularly used in modern motor vehicles. An efficient operation of these devices requires a suitable communications network.
Up to now, different bus systems have frequently been used in motor vehicles, such as the Local Interconnect Network (LIN), the Controller Area Network (CAN), or the FlexRay.
With an increasing complexity of the regulating and control devices and with a growing number of the above-mentioned devices, the demand for networks, such as the need for Ethernet networks, is rising.
It is an object of the invention to provide a conversion device which contributes to an efficient and reliable data transfer. According to a further aspect, it is an object of the invention to create a communications network which contributes to an efficient and reliable data transfer.
According to a first aspect, the invention includes a conversion device which is designed for converting message units of a first communications protocol, which are received on the input side, to container messages of a second communications protocol. A specified maximal dwell duration in the conversion device is assigned to each message unit. The conversion device is designed for assigning message units with a same recipient address received on the input side to a container message for the respective recipient address and for forwarding the respective container message when the maximal dwell duration of at least one of the message units assigned to it has expired or a specified maximal data volume is assigned to the respective container message, induced by the message units assigned to it.
According to a second aspect, the conversion device is arranged in a communications network having a first subnetwork based on a first communications protocol, and a second subnetwork based on a second communications protocol. The conversion device is arranged at an interface between the first subnetwork and the second subnetwork. The communications network may also include further subnetworks, such as an additional subnetwork which is based on the first communications protocol.
The conversion device may, for example, also include a gateway or be a gateway, which may also be called a converting gateway.
The conversion device is distinguished by the fact that, during its operation, depending on the arrival time and the respective maximal dwell duration, as required, several and frequently even a plurality of message units can be assigned to a single container message, and therefore their available data volume, on the one hand, can be utilized as well as possible and thus the number of container messages which, in each case, are to be sent to the respective recipient address can be minimized, and, on the other hand, it can be ensured that the respective maximal dwell time in the conversion device is not exceeded for each message unit.
In this manner, a timely transmission of the respective message units on the output side of the conversion device can be guaranteed. Furthermore, however, the number of the container messages to be sent to the respective recipient address can be minimized which, particularly in the case of units which receive the respective container message, keeps their loading as low as possible. In this case, for example, the receiving of a respective container message is connected with an interrupt treatment. By providing a respective container message for the respective recipient address, a unicast as well as a multicast therefore becomes possible for each addressed recipient or for each addressed recipient group.
The maximal data volume can be appropriately predefined and thereby ensure that all of the message units assigned to the container message can, in fact, be accommodated in the latter.
Furthermore, the conversion device contributes to the fact that particularly time-critical message units with a correspondingly briefly predefined maximal dwell duration are forwarded correspondingly promptly in a respective container message. In this connection, other message units assigned to the respective container message then correspondingly also benefit from a quick forwarding of the container message.
In addition, by minimizing the number of the respective sent container messages, a network load of the second subnetwork based on the second communications protocol can be kept as low as possible, which contributes to the fact that correspondingly time-critical message units in respective container messages can be sent particularly reliably and also rapidly by way of the second communications network.
Correspondingly, a contribution can also be made to keeping the loading of the respective receiving unit of the container message as low as possible. Furthermore, a contribution can be made to transporting particularly real-time-critical message units especially in the second subnetwork.
According to an advantageous further development, in the case of at least a partial quantity of message units, an identification is assigned to each of the respective message units, and the conversion device is designed for making the assigned maximal dwell time available as a function of the respective identification of the messaging unit. In this fashion, the respective assigned maximal dwell time can easily be made available; thus, as required, by way of a corresponding data bank which, if necessary, may also be designed outside the conversion device and to which, as required, several conversion devices can also have access. In this case, the respective identification may, for example, be a so-called message ID.
According to a further advantageous development, in the case of at least a partial quantity of the message units, the respective message units each include information regarding the assigned maximal dwell duration. In this case, the conversion device is designed to extract the maximal dwell duration assigned to the respective message unit from the latter. In this manner, the respective maximal dwell duration can easily be determined, specifically directly while using the respective message unit.
According to further advantageous developments, the first communications protocol is CAN-bus-based, FlexRay-based, and/or LIN-bus-based. According to a further advantageous development, the second communications protocol is Ethernet-based. In principle, for example, the first communications protocol may be Ethernet-based and the second communications protocol may be CAN-bus-based, FlexRay-based, or LIN-bus-based.
Advantageously, the conversion device and/or the communications network is arranged in a vehicle. They may, for example, also be arranged in an airplane or in a production system.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.